There is a fundamental problem with integrated ego style batteries: they all use the same style LiIon, LiPO, etc. battery inside that almost every other PV on the planet does. LiIon's have many advantages in a PV, but they cannot be recharged an infinite number of times. There is a limit which starts at around 300 charge cycles with a very large margin on either side. Regardless of the source, this margin can be very unpredictable. We used to use tons of industrial LiIon batteries, and the statistical variation in recharge cycles would drive our QC people crazy. Cell phones and PC's use the same technology in their batteries; just ask any tech in those fields to show you the mountain of failed batteries waiting to be disposed of. Some last a few years others last a few months.Very few manufactures of these products will give you any more than 30 day guarantee on a battery.
I don't use ego style batteries any longer, having gone over to VV PV's and Reo's. But even with these devices, I end up tossing about a battery a month and I do not buy garbage batteries.
So you make your choice: the slick, slim style and convenience of an ego vs. the much larger bulk of another(and more to far more expensive) PV with replaceable batteries. I get my batteries from China from DealExtreme and they end up costing about $2-3, even with shipping.
It is fairly easy to get to the 300 AVERAGE number of recharges and quickly as well. If you are a heavy vaper, you could easily be recharging your battery twice a day. The numbers will catch up to you sooner or later. Bad QC on the device itself will only accelerate the process.Even a bullet proof device like my ProVari went back to the shop 2 times before they got it right. It has been flawless since, and the service was without problems.
No device is perfect, so we vapers will just have to live with the imperfections. Analogs were far simpler: you ran out, you bought some more. On the other hand, do you still want to be smoking?